A specific gas-chromatographic method was developed for determination of N-acetylprocaine amide in plasma and urine, using 4-amino-N-(2-piperidinoethyl)benzamide as an internal standard. The investigation was performed in 50 cardiac patients who had reached steady-state plasma concentrations of procaine amide. 2 The plasma concentrations of the acetylated metabolite varied between 1.0 and 15.0 mg/ml and were thus of the same order of magnitude as those of the parent drug. Especially high plasma levels of the metabolite were seen in patients with poor kidney function. 3 The urinary excretion of the metabolite varied markedly between individuals and ranged between 6 and 52% of the administered daily dose. There was a clear tendency towards higher rates of acetylation of procaine amide in patients with short plasma half-lives of isoniazid, i.e. the phenotype rapid acetylators. Because of coexisting therapy with other drugs and impaired renal function in some patients studies are required in healthy human volunteers to ascertain whether the acetylation of procaine amide and isoniazid are mediated by the same enzyme system.

The content of 21 elements (As, Au, Br, Ca, Cd, Co, Cr, Cs, Cu, Fe, Hg, K, La, Mo, P, Rb, Sb, Sc, Se, W and Zn) in normal epidermis has been determined with the aid of neutron activation analysis. The dermal loss of these elements via desquamation has been calculated in view of its possible importance in balance studies. For the bulk elements Ca, K and P, the calculated daily loss is considered to be negligible. For some of the trace elements, however, the loss may be appreciable. The daily loss of Fe by desquamation may be as much as one fourth of the daily urinary iron excretion; the corresponding fraction for Co, Cu, and Zn is one tenth.

The metabolism of procaine amide was studied in 41 cardiac patients who had achieved steady state plasma concentrations of the drug. Acetylated procaine amide accounted for 31 +/- 12% (range 16-63%) of the overall urinary recovery of the drug and is therefore a main metabolite in man. Plasma levels of the metabolite were usually lower but sometimes exceeded those of the parent compound with variations between 1 and 15 mug/ml. The metabolite had a weaker effect than procaine amide on the maximal electrical driving velocity of isolated atrial strips from guinea pig.

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